Fair Value (Assets and Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions	Jan. 28, 2017	Jul. 30, 2016
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	$ 70,056	$ 64,602
Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	118	385
Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	59	54
Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	50	0
Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	43
Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	8,635	6,049
Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	276	0
Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	30	0
Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	22,832	26,544
Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	30,698	24,292
Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	195	0
Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,397	2,817
Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,205	1,100
Available-for-sale investments: | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,006	1,868
Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,614	1,504
Level 1
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	10,249	7,553
Level 1 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	0	0
Level 1 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	8,635	6,049
Level 1 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,614	1,504
Level 2
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	59,807	57,048
Level 2 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	118	384
Level 2 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	59	54
Level 2 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	50	0
Level 2 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	43
Level 2 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 2 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	276	0
Level 2 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	30	0
Level 2 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	22,832	26,544
Level 2 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	30,698	24,292
Level 2 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	195	0
Level 2 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,397	2,817
Level 2 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,205	1,100
Level 2 | Available-for-sale investments: | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,006	1,868
Level 2 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	1
Level 3 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	1
Level 3 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	0	0
Level 3 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	$ 0	$ 0